Dimerization of olefins with supported palladium catalyst

ABSTRACT

Palladium salts supported on material such as alumina or silica alumina provide effective catalysts for the dimerization or codimerization of Alpha -olefins such as ethylene or propylene in a heterogenous reaction system. The products are easily separated from the catalyst which has a high degree of activity for long periods of time.

1 Sept. 11, 1973 1 1 DIMERIZATION OF OLEFINS WITH SUPPORTED PALLADIUM CATALYSTS [751 Inventors: Robert P. Arganbright; Edward J.

Miklas, both of Houston, Tex.

[73] Assignee: Petro-Tex Chemical Corporation, Houston, Tex.

[22] Filed: July 29, 1970 [21] Appl. No.: 59,370

[52] U.S. Cl 260/683.l5 R, 252/438, 252/441, 260/683.15 B [51] Int. Cl C07c 3/12, C07c 3/18 [58] Field of Search 260/683.15 B; 252/441 [56] References Cited UNITED STATES PATENTS 2,656,398 10/1953 DeVault 260/683.15 3,354,236 11/1967 Klein 260/683.15 2,825,721 3/1958 Hogan et a1. 260/683.l5 X 3,442,964 5/1969 Oldham 260/683 l5 X 3,379,706 4/1968 Wilke 260/683.15 X 3,131,223 4/1964 Smidt et a1 252/441 X 3,403,108 9/1968 Leftin et a1. 252/441 X 3,407,223 10/1968 Kominami et al. 252/441 X 3,013,066 12/1961 Alderson 260/683.l5 X

3,361,840 1/1968 Kohll et al. 260/683.l5 3,483,269 12/1969 Magoon et al..... 260/683.l5 3,592,869 7/1971 Cannell 260/683.15

FOREIGN PATENTS OR APPLICATIONS 711,042 2/1968 Belgium OTHER PUBLICATIONS Acres et al., J. Catalysis, Vol. 6, No. l (1966) pages Ketley et al., lnorganic Chemistry, Vol. 6, No. 4 (1967) pages 657-663.

Rony, Chemical Engineering Science, V01. 23 (1968) pages 1021-1034.

Primary Examiner-Paul M Coughlan, .lr. Att0mey--G. Baxter Dunaway [5 7] ABSTRACT 16 Claims, No Drawings DEMERIZATION F OLEFINS WITH SUPPORTED PALLADIUM CATALYSTS This invention relates to a novel catalytic process for the preparation of dimers and co-dimers of alphaolefins. More particularly the process employs particular catalysts of palladium. 1

it is often desirable to convert lower olefinic compounds to higher olefinic compounds. For example, in the catalytic cracking of petroleum products substantial quantities of ethylene are produced which it is de sirable to dimerize to the more valuable butene. Similarly propylene dimers have a wide range of uses. For example, they may be used as fuel or fuel components. They are also useful chemical intermediates. Isoprene can be produced by dimerizing propylene to produce 2-methylpentene-2 which is dementhanated.

U. S. Pat. No. 3,013,066 taught that dimers and codimers of alpha-olefins could be prepared in an anhydrous reaction medium in the presence of salts of the noble metals of Group VIII of the Periodic Table. This reaction required high pressure, i.e., at least atmospheres and preferably between 50 and 1,500 atmospheres at temperatures of to 275 C.

It is an object of the present invention to provide a heterogenous catalytic process wherein the catalyst is easily removed from the system by virtue of its substantial insolubility therein. Another object of the invention is to provide a process that can be operated under much milder conditions than those described above. Another object is to provide a catalytic process that does not require an inert reaction medium. These and other objects of the invention will become apparent from the description of the invention.

These and other objects are obtained by dimerizing or co-dimerizing a-olefins in the presence of particular supported palladium salt catalysts. The catalyst may be prepared by methods known for the preparation of supported catalysts, e.g., by impregnation or coprecipitation techniques. Noloss of palladium .or palladium salt from the support was noted as a result of the use as described herein.

The palladium salts found useful in the present process are the inorganic acid salts of palladium, in particular those acids which are considered strong acids, i.e., HCl, HBr, HI, HNO and H 80 Some particular inorganic acid salts are palladium chloride, palladium bromide, palladium iodide, palladium nitrate, palladium sulfate or mixtures of these salts. Particularly preferred salts are palladium chloride .or palladium nitrate.

A wide variety of supports can be used for the palladium salt such as silica, silica-alumina, alumina,'alumi- A The catalyst pellets prepared in Example 1 num phosphate, zirconia, boria, titania, magnesia,

pumice, kieselguhr, firebrick and the like. Particularly preferred are alumina phosphate, silica-alumina. and alumina. The supported palladium salt catalyst can be used in a fixed bed or in a movable particulate form, for example, in a slurry or a fluidized bed.

I The dimerization or co-dimerization is carried out in either vapor or liquid phase. The pressure can be in the range of 0 to 50 atmospheres or more such as that employed in the prior art. Generally sufficient pressure is employed to maintain the particular state desired, i.e vapor or liquid phase, although for example more pressure can be employed than is necessary to maintain the liquid phase. Generally the temperature of the reaction will not be too severe and will range from about' 0 to l 50 C, preferably 25 to C.

In addition to the a-olefin reactant the reaction can contain an inert diluent or medium although it is not necessary. In selecting an inert-diluent or medium, care should be exercised that the diluent or medium is not also a solvent for the palladium salt. Generally the halogenated solvents, such as chloroform or chlorobenzene and organic nitro compounds such as 2-nitro-propane, dinitrotoluene, nitrocyclohexane and the like would not be suitable. Suitable inert diluents or medium would include the alkyl and aromatic hydrocarbons such as butane, hexane, octane, benzene, toluene, xylene and the like.

The reaction can be conducted as a batch operation or in a continuous manner. The fluid reactants can be conducted through the reaction chamber at a wide range of flow rates. The optimum flow rate will depend on such variables as the temperature of the reaction, pressure, particle size and the like. Generally the flow rates will be within the range of about 10 to 120 volumes of olefin to be reacted per volume of reaction 'zone containing catalyst per hour (referred to as GHSV).

The amount of palladium salt on the support is relatively small. Any ratios or reference herein refers to the surface-of the catalyst in contact with the fluid phase during the dimerization or codimerization. Generally, there willbe about 2 to 5 wt. percent palladium salt on the support.

Preferred a-olefins contemplated in the present invention contain two to nine carbon atoms. Some suitable mono-olefins are ethylene, propylene, butylene, hexene and nonene. The chains may be straight or branched. A preferred group of mono-a-olefins is ethylene, propylene, butene or mixtures thereof.

EXAMPLE 1 A solution of palladium chloride was prepared by dissolving 4 gramsof PdCl, in 60 ml of 3 M HCl solution. Twenty ml of this solution was added to 50 ml of a silica-alumina-support (87.3 percent silica, 12.4 percent alumina, surface area 425-450 m] g designated Houdry 8-9.0) placing about 3.17 weight percent PdCl, on the support. The catalyst wasdried at 200 C.under vacuum. t

, EXAMPLE 2 I were placed in a 1-inch diameter 13" tubular reactorand ethylene was fed at 20 ml/minute at 25 C. and 1 atmosphere of pressure/After 1 hour, analysis of the effluent showed 39 wt. percent n-butene-Z, 59.4 wt. percent ethylene and a trace of n-butene-l. After 60 hours on stream the effluent was 43 wt. percent'n-butene-Z and 57 wt. percent ethylene. The temperature was raised to 50 C. and after [/2 hour the system stabilized at 45 wt.

. percent n-butene-Z and 55 wt. percent ethylene.

EXAMPLE 3 In a manner similar to Example 1, 2.6 g. of PdCl was deposited on 100 ml. of alumina (Alcoa H-151 previously treated with a percent aqueous HF solution and dried). After drying at 200 C. under vacuum, this catalyst was placed in a tubular glass reactor, cooled to 25 C. and ethylene was fed at 20 ml/min. After 16 hours on stream, the effluent analyzed as 97.5 percent ethylene and 2.5 percent butene of which 15 percent was butene-l and 85 percent butene-2.0n increasing the reactor temperature to 50 C., the effluent after 1 hour analyzed as 6.0 percent butene and 94 percent ethylene.

Changing the feed to 20 ml/min. propylene and ml/min. ethylene over this catalyst at 50 C. produces an effluent analyzed as 84.3 percent ethylene and propylene, 14.6 percent butene and 1.1 percent npentene-Z.

EXAMPLE 5 50 ml. of Alcoa H-151 alumina was treated with excess phosphoric acid and then was dried under vacuum at 200 C. The alumina was treated further after drying, with sufficient PdCl in 3M HCl solution to give about EXAMPLE 7-10 In a manner similar to Example 1, 3.6 g. of PdCl was deposited on an aluminum phosphate (Girdler T-1067) surface area of 47 m /g and 3.82 PdCl deposited on alumina (Alcoa H-l5l-previously treated with 10 percent H PO and dried at 400 C. containing by typical analysis 85 wt. A1 0 6.3 wt. SiO 2.0 wt. Na O and 0.15 Fe o -surface area 350 m lg).

1n examples 7-9, 50 cc of the PdCl -aluminum phosphate catalyst was charged to a tubular reactor. In Example 10, 50 cc of the PdCl -alumina was charged to the reactor. The conditions and olefin feeds are shown in the Table. Yields were comparable to those of previous examples.

The corrosion problems encountered in conventional liquid phase homogenous palladium salt reactions such as those of U.S. Pat. No. 3,013,066 are avoided in the present heterogenous process since the palladium salts do not come in contact with the reactor. This advantage allows the use of less expensive materials of construction for reactors, separation and recovery equipment and the like. Additionally, the likelihood of the loss of the expensive palladium salts is substantially eliminated or reduced.

ABLE

Fixed Bed-50cc Catalyst Charge Temp "C Feed Products 125 Ethylene cis-and trans-butenes. and butene-1 125 Propylene 2,3-dimethybutene-2. n hexene-3 and Z-methylpentane-Z 125 Ethylene n-pentene-Z. mpentene-l. 2methyl Propylene butene-2 and traces of Z-methyl. butene-1 and isopropyl chloride. 125 Ethylene Butylenes Treated with 10 wt. H3PO4 and dried at 400 C prior to impregnation.

2.7 percent PdCl by wt. on the support. The catalyst was dried again at 200 C. under vacuum and was placed in a tubular reactor. A mixture of ethylene and propylene at 5 ml/min. each gave an effluent containing 6.3 percent butene and 6.0 percent n-pentene-2 and unreacted feed.

This catalyst lost activity at higher temperatures up to 150 C. The catalyst could be regenerated to its original activity by treatment with HCl and air at 200 C. (flow rates 20 ml/min. HCl and ml/min. air) for 1 hour. After purging with nitrogen the catalyst was cooled to 65 C. where a feed of propylene (50 ml/min.) and ethylene (10 ml/min.) gave an effluent of 10 percent pentenes, 7 percent butenes and unreacted feed.

EXAMPLEQ6 2 ml. of aluminum phosphate (Girdler T-1067) was treated with excess 10 percent palladium nitrate solution, filtered and dried under vacuum at 50 C. This catalyst was placed in a 50 ml. Erlenmeyer flask stoppered with a rubber septum. The flask was purged and pressured to 5 psig with ethylene. Some immediate dimerization to butene was noted. On standing for about 64 hours at room temperature, approximately 25 C., all of the ethylene had dimerized to 80 percent transbutene-2, 15 percent cis-butene-Z and 5 percent butene-l.

The invention claimed is:

1. A process for preparing dimers and co-dimers of a-monoolefins consisting essentially of contacting an a-monoolefin reactant selected from ethylene, propylene or mixtures of ethyleneand propylene in the presence of a catalytic amount of a material consisting of an inorganic acid salt of palladium on a support which is aluminum phosphate, silica-alumina or alumina at a temperature of between 0 and C. and at a pressure of between 0 and 50 atmospheres.

2. The process according to claim 1 wherein the inorganic acid salt of palladium is selected from the group consisting of palladium chloride, palladium bromide, palladium iodide, palladium nitrate, palladium sulfate and mixtures thereof.

3. The process according to claim 2 wherein the inor- 13. The process according to claim 1 wherein an inert diluent is present with the a-monoolefin reactant.

14. The process according to claim 1 wherein said a-monoolefin is ethylene.

15. The process according to claim 1 wherein said a-monoolefin is propylene.

16. The process according to claim 1 wherein said a-monoolefin is a mixture of ethylene and propylene. =8 

2. The process according to claim 1 wherein the inorganic acid salt of palladium is selected from the group consisting of palladium chloride, palladium bromide, palladium iodide, palladium nitrate, palladium sulfate and mixtures thereof.
 3. The process according to claim 2 wherein the inorganic acid salt of palladium is palladium chloride or palladium nitrate.
 4. The process according to claim 1 wherein the temperature is between 25* and 60* C.
 5. The process according to claim 1 wherein said Alpha -monoolefins are in the gaseous phase.
 6. The process according to claim 5 wherein the inorganic acid salt of palladium is palladium chloride.
 7. The process according to claim 6 wherein the support is silica-alumina and the Alpha -monoolefin comprises ethylene.
 8. The process according to claim 7 wherein the Alpha -monoolefin comprises ethylene and propylene.
 9. The process according to claim 6 wherein the support is alumina and the Alpha -monoolefin comprises ethylene.
 10. The process according to claim 1 wherein the inorganic acid salt of palladium is palladium nitrate.
 11. The process according to claim 6 wherein the support is aluminum phosphate and the Alpha -monoolefin comprises ethylene.
 12. The process according to claim 1 wherein the support is aluminum phosphate and the Alpha -monoolefin is propylene.
 13. The process according to claim 1 wherein an inert diluent is present with the Alpha -monoolefin reactant.
 14. The process according to claim 1 wherein said Alpha -monoolefin is ethylene.
 15. The process according to claim 1 wherein said Alpha -monoolefin is propylene.
 16. The process according to claim 1 wherein said Alpha -monoolefin is a mixture of ethylene and propylene. 